Naturally occurring bacteria can also ferment cellulose, but they do it at lower temperatures that require the use of an expensive enzyme called cellulase, says study author Professor Lee Lynd of Dartmouth College.

Heat tolerant

ALK2 can ferment all the sugars present in biomass and can do it at 50 degrees Celsius, compared with conventional microbes that cannot function above 37 degrees Celsius.

At higher temperatures, the fermentation process requires two and a half times less cellulase in one controlled experiment, says Lynd.

Doing it the natural way produces organic acids in addition to the ethanol, while ethanol is the only organic product of fermentation with the new bacteria, he adds.

Lynd says that ALK2 is more efficient than the microorganisms now in use in breaking down all five sugars present in cellulosic biomass.

"This bug will ferment them all and it will ferment them at the same time," he says.

The researchers say that cellulosic ethanol has almost no net emissions of climate-warming greenhouse gases because the carbon dioxide captured in growing the plants that go into it roughly equals what is emitted while running an engine.

In addition to being a professor at Dartmouth, Lynd is chief scientific officer and co-founder of Mascoma Corp, a company working to develop processes to make cellulosic ethanol.